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@ARTICLE{Maddison:28021,
author = {Maddison, G. P. and Brix, M. and Budny, R. and Charlet, M.
and Coffey, I. H. and Cordey, J. G. and Dumortier, P. and
Erents, S. K. and Hawkes, N. C. and von Hellermann, M. and
Hillis, D. L. and Hogan, J. and Horton, L. D. and Ingesson,
L. C. and Jachmich, S. and Jackson, G. L. and Kallenbach, A.
and Koslowski, H. R. and Lawson, K. D. and Loarte, A. and
Matthews, G. F. and McKee, G. R. and Meigs, A. G. and
Messiaen, A. M. and Milani, F. and Monier-Garbet, P. and
Murakami, M. and Nave, M. F. F. and Ongena, J. and Puiatti,
M. E. and Rachlew, E. and Rapp, J. and Sharapov, S. and
Staebler, G. M. and Stamp, M. and Strachan, J. D. and
Telesca, V. M. and Tokar, M. Z. and Unterberg, B. and
Valisa, M. and Zastrow, S. A.},
title = {{I}mpurity-seeded plasma experiments on {JET}},
journal = {Nuclear fusion},
volume = {43},
issn = {0029-5515},
address = {Vienna},
publisher = {IAEA},
reportid = {PreJuSER-28021},
pages = {49 - 62},
year = {2003},
note = {Record converted from VDB: 12.11.2012},
abstract = {Scaling to larger tokamaks of high confinement plasmas with
radiating edges, induced by impurities, is being studied
through internationally collaborative experiments on JET. In
campaigns till the end of 2000, three different regimes have
been explored. A small number of limiter L-mode discharges
seeded with neon have most closely repeated the approach
used on TEXTOR-94, but different collisionality and particle
transport in JET impede central peaking of the density
associated with improved confinement. Divertor L-modes at
intermediate density, again with neon injection, have
pursued transiently enhanced states found on DIII-D.
Confinement up to H-mode quality, together with radiation
fractions of approximate $to40\%,$ have briefly been
obtained, though central Z(eff) quickly increases. Most
effectively, neon and argon seeding of higher density ELMy
H-modes formed mainly at low triangularity on the septum of
the MkIIGB divertor, resembling a pumped-limiter
arrangement, have been examined. Good confinement has been
sustained at densities close to the Greenwald level in
'afterpuff' (AP) phases following the end of main gas
fuelling, for little change of central Z(eff) but up to
approximate $to60\%$ radiation. Outstanding normalized
properties up to H-97 = 0.99 at f(Gwd) = 0.94 have thus been
achieved, above the conventional H-mode density limit for
diverted plasmas. Stationarity of states has also been
extended to many energy confinement times by including low,
extra gas inputs in the 'AP', suggestive of an optimized
fuelling scheme. Further development in 2001 is reported
separately in [1]. Accompanying ELMs are generally reduced
in frequency though not evidently in size, electron pedestal
pressure being almost unchanged from unseeded behaviour.
There are indications of the most favourable impurity
species scaling with plasma parameters, performance,
radiation and its concentration within a mantle all
increasing with argon compared to neon in JET. These
benefits in terms of integrated properties are just as
required for long burning pulses in ITER, supporting its use
of a radiating mantle to assist not only power exhaust but
performance too. Impurity-seeded H-modes can therefore
contribute directly to next-step scenario development.},
keywords = {J (WoSType)},
cin = {IPP},
ddc = {530},
cid = {I:(DE-Juel1)VDB181},
pnm = {Kernfusion und Plasmaforschung},
pid = {G:(DE-Juel1)FUEK250},
shelfmark = {Physics, Fluids $\&$ Plasmas / Physics, Nuclear},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000180953100006},
doi = {10.1088/0029-5515/43/1/306},
url = {https://juser.fz-juelich.de/record/28021},
}